Initially, I use to think merit is by chance ( i.e something that will just happen) or lengthy article ( i.e writing too many paragraphs and the rest of them), but I have come to realize that, it is more than that.
I have being discouraged several times because of my numerous posts and replies yet no merit then. Even now, some times I use to be discourage. However, the only way to get merit is by posting quality article ( that is what determines merit) which almost everybody is aware of now.
In summary, don't look at the quantity of post you have make so far but instead try to adjust, I mean improve in your posts, above all be consistent and patient that is the key.
Once you have the key, it should be easier for you to do it. What I mean is, as long as you consistently produce quality posts and are patient with appreciation from other members for your efforts to produce quality posts, sooner or later there will be members who give merit to your posts. Always look for opportunities that can bring merit and often post quality content on boards or topics that are frequently visited by Merit Source. You have to approach them by showing something valuable so that they appreciate your posts.